Let capture_dev_user_pmode_find() say "not found".

"Not found" is different from "found, and false".  Have it return a
boolean "did I find the property" indication and, if it did, supply the
property value through a pointer.

Change-Id: Iaa942ea346410b35e512ff1a3821cbf60c88dfd6
Reviewed-on: https://code.wireshark.org/review/7916
Reviewed-by: Guy Harris <guy@alum.mit.edu>

ui/capture_ui_utils.c

@@ -237,9 +237,17 @@ capture_dev_user_snaplen_find(const gchar *if_name, gboolean *hassnap, int *snap
 }
 
 gboolean
-capture_dev_user_pmode_find(const gchar *if_name)
+capture_dev_user_pmode_find(const gchar *if_name, gboolean *pmode)
 {
-  return (capture_dev_get_if_int_property(prefs.capture_devices_pmode, if_name) != 0);
+  int value;
+
+  value = capture_dev_get_if_int_property(prefs.capture_devices_pmode, if_name);
+  if (value == -1) {
+    /* Not found or bad. */
+    return FALSE;
+  }
+  *pmode = (value != 0);
+  return TRUE;
 }
 
 gchar*

ui/capture_ui_utils.h

@@ -85,8 +85,14 @@ gboolean capture_dev_user_snaplen_find(const gchar *if_name, gboolean *hassnap,
 /**
  * Find user-specified promiscuous mode that matches interface
  * name, if any.
+ *
+ * @param if_name The name of the interface.
+ * @param pmode Pointer to a variable to be set to TRUE if promiscuous
+ * mode should be used and FALSE if it shouldn't be used.
+ *
+ * @return TRUE if found or FALSE if not found.
  */
-gboolean capture_dev_user_pmode_find(const gchar *if_name);
+gboolean capture_dev_user_pmode_find(const gchar *if_name, gboolean *pmode);
 
 /**
  * Find user-specified capture filter that matches interface

ui/gtk/capture_dlg.c

@@ -1272,7 +1272,7 @@ insert_new_rows(GList *list)
       device.buffer = global_capture_opts.default_options.buffer_size;
     }
 #endif
-    if ((device.pmode = capture_dev_user_pmode_find(if_string)) == -1) {
+    if (!capture_dev_user_pmode_find(if_string, &device.pmode)) {
       device.pmode = global_capture_opts.default_options.promisc_mode;
     }
     if (!capture_dev_user_snaplen_find(if_string, &device.has_snaplen,
@@ -5688,8 +5688,7 @@ create_and_fill_model(GtkTreeView *view)
       }
       if (!linkname)
           linkname = g_strdup("unknown");
-      pmode = capture_dev_user_pmode_find(device.name);
-      if (pmode != -1) {
+      if (capture_dev_user_pmode_find(device.name, &pmode)) {
         device.pmode = pmode;
       }
       if (capture_dev_user_snaplen_find(device.name, &hassnap, &snaplen)) {

ui/gtk/prefs_capture.c

@@ -1121,6 +1121,7 @@ ifopts_edit_ifsel_cb(GtkTreeSelection	*selection _U_,
 #endif
 	gint                snaplen;
 	gboolean            hide, hide_enabled = TRUE, hassnap = FALSE, pmode;
+	gboolean            pmode_pref;
 	if_capabilities_t  *caps;
 	gint                selected = 0;
 
@@ -1163,8 +1164,8 @@ ifopts_edit_ifsel_cb(GtkTreeSelection	*selection _U_,
 
 	if (prefs.capture_prom_mode) {
 		gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(if_pmode_cb), TRUE);
-	} else if (capture_dev_user_pmode_find(if_name) != -1) {
-		gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(if_pmode_cb), capture_dev_user_pmode_find(if_name));
+	} else if (capture_dev_user_pmode_find(if_name, &pmode_pref)) {
+		gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(if_pmode_cb), pmode_pref);
 	} else {
 		gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(if_pmode_cb), FALSE);
 	}
@@ -1662,9 +1663,7 @@ ifopts_options_add(GtkListStore *list_store, if_info_t *if_info)
 	if (prefs.capture_prom_mode) {
 		pmode = TRUE;
 	} else {
-		if ((pmode = capture_dev_user_pmode_find(if_info->name)) != -1) {
-			pmode = capture_dev_user_pmode_find(if_info->name);
-		} else {
+		if (!capture_dev_user_pmode_find(if_info->name, &pmode)) {
 			pmode = FALSE;
 		}
 	}

ui/iface_lists.c

@@ -276,7 +276,7 @@ scan_local_interfaces(void (*update_cb)(void))
         device.local = TRUE;
         device.if_info = *temp;
         device.last_packets = 0;
-        if ((device.pmode = capture_dev_user_pmode_find(if_info->name)) == -1) {
+        if (!capture_dev_user_pmode_find(if_info->name, &device.pmode)) {
             device.pmode = global_capture_opts.default_options.promisc_mode;
         }
         if (!capture_dev_user_snaplen_find(if_info->name, &device.has_snaplen,

ui/qt/capture_interfaces_dialog.cpp

@@ -498,8 +498,7 @@ void CaptureInterfacesDialog::updateInterfaces()
                 }
             }
 
-            pmode = capture_dev_user_pmode_find(device->name);
-            if (pmode != -1) {
+            if (capture_dev_user_pmode_find(device->name, &pmode)) {
                 device->pmode = pmode;
             }
             if (capture_dev_user_snaplen_find(device->name, &hassnap, &snaplen)) {